(a) Field of the Invention
The present invention relates to an apparatus and a method for transmitting a tag.
(b) Description of the Related Art
In a passive RFID system, a tag having target information does not have power and a device for controlling a wireless signal. Accordingly, the tag constituting the passive RFID system receives a carrier signal in a wireless environment from a reader to generate power, and communicates with the reader based on backscattering. Since the above passive RFID system may provide information on a separate target, has a high recognition distance as compared with a barcode, and may simultaneously recognize a plurality of tags, the passive RFID system has been used in various fields.
In recent years, the RFID system has been used to manage components in airline, vehicle, ship building, and steel fields. The RFID system requires read/write of large capacity data at a high speed using a tag user memory of 32 Kbyte or greater or 64 Kbyte or greater. Further, there is a need for a technology for recognizing an object which is moved at a high speed in train and conveyor application fields.
However, there are limitations to satisfy the requirements due to low transmission speed of data as an existing passive RFID technology.
A Miller encoding scheme in an ISO/IEC 18000-63 standard which is an international standard has been proposed. In the existing Miller encoding scheme, as a Miller subcarrier, a total of 4 types of waveforms are generated. However, each waveform is transmitted by allocating one bit to each waveform. For example, S1(t) and S3(t) having different phases may generate different Miller sub-carriers, but transmit only one bit. Accordingly, data transmission speed is low.